Wings Forum

Angle of Attack insturment

Angle of Attack insturment

Posted: Mon Oct 08, 2007 9:06 pm

by DaveU

I just finished, almost, the installation of the Alpha Systems angle of attack. I wish I had understood the utility of this instrument when I was building. I am happy with the retrofit of the probe in the wing. I think it is sturdy and will hold the probe safely. I like the housing around the indicator, and the tubing route was simple. Here are pictures of the updated AOA from Alpha Systems.

Dave

Posted: Tue Oct 09, 2007 2:00 am

by Dave Krall CFII SEL SES

Looks cool, nice instrument panel as well.
We're plumbing in the AoA and AI for the Enigma glass unit now.

Posted: Sun Oct 28, 2007 1:15 pm

by b1x4nqb

Dave,

What is it like to fly the plane now with the AOA? Can you give us any feedback as to your impressions of flying with it? Do you find it valuable?

Thanks,
Paul

Posted: Sun Oct 28, 2007 2:01 pm

by Dave Krall CFII SEL SES

b1x4nqb wrote:Dave,

What is it like to fly the plane now with the AOA? Can you give us any feedback as to your impressions of flying with it? Do you find it valuable?

Thanks,Paul

It's not flying yet but I'll let you know soon. Personally I don't expect it too be very valuable, except maybe in IMC, we'll see. It's not a feature that I bought the Enigma for, it's just there.

Posted: Sun Oct 28, 2007 7:41 pm

by DaveU

I have about 4 hours now on the plane with the Alpha Systems lift reserve indicator. It is great. I use it during all phases of flight with the exception of cruise. It is nice to know when you are just a smidge above stall, to give that little margin of safety. I can climb out at best angle about 45 mph indicated solo with full fuel. This gives me about 900 fpm and an incredibly steep deck angle. This is steeper than I would feel comfortable climbing without the AOA. Testing the calibration I was flying at minimum controllable airspeed, 35 mph indicated, 4000 rpms, and keeping the needle right at alpha. I was able to make shallow turns, full control, and no stall. Pull back a little on the stick and the nose bobs into a stall. push the stick so the needle comes back to alpha, stall recovery complete, little loss of altitude.

It automatically corrects for aircraft loading and density altitude. No need to estimate stall speed for every load condition. Just start the takeoff run, when the needle comes up through into the white, pull back on the stick and hold the needle in the white and it climbs with a safety margin above stall. Same for approaches, fly the downwind at the top of the white, base in the middle of the white and final at the lower end of the white, at very short final, bottom of the white, and there is not enough energy left to float, I add a shot of power, flare and touchdown. This will allow the shortest landing possible, with a safety margin.

I think that this is the most important flight instrument on the panel. Airspeed is there to cross check. I continue to scan the airspeed, and the AOA during takeoff, landing and any maneuvering flight.

I am a big advocate of the instrument, and would not fly this type of aircraft without it. It is useful to extract the performance out of the plane and still keep a margin of safety.

Dave U
#97

Posted: Sun Oct 28, 2007 11:14 pm

by Dave Krall CFII SEL SES

DaveU wrote:I have about 4 hours now on the plane with the Alpha Systems lift reserve indicator. It is great. I use it during all phases of flight with the exception of cruise. It is nice to know when you are just a smidge above stall, to give that little margin of safety. I can climb out at best angle about 45 mph indicated solo with full fuel. This gives me about 900 fpm and an incredibly steep deck angle. This is steeper than I would feel comfortable climbing without the AOA. Testing the calibration I was flying at minimum controllable airspeed, 35 mph indicated, 4000 rpms, and keeping the needle right at alpha. I was able to make shallow turns, full control, and no stall. Pull back a little on the stick and the nose bobs into a stall. push the stick so the needle comes back to alpha, stall recovery complete, little loss of altitude.

It automatically corrects for aircraft loading and density altitude. No need to estimate stall speed for every load condition. Just start the takeoff run, when the needle comes up through into the white, pull back on the stick and hold the needle in the white and it climbs with a safety margin above stall. Same for approaches, fly the downwind at the top of the white, base in the middle of the white and final at the lower end of the white, at very short final, bottom of the white, and there is not enough energy left to float, I add a shot of power, flare and touchdown. This will allow the shortest landing possible, with a safety margin.

I think that this is the most important flight instrument on the panel. Airspeed is there to cross check. I continue to scan the airspeed, and the AOA during takeoff, landing and any maneuvering flight.

I am a big advocate of the instrument, and would not fly this type of aircraft without it. It is useful to extract the performance out of the plane and still keep a margin of safety.

Dave U#97

Dayum Dave, sounds like that AoA gismo could put us CFIs out of business! One of my favorite exercises with any level student is not partial panel but, complete coverage of the panel with a jacket or shirt. No AI, nothin' on the panel at all.
BTW: Do you know your aircraft's stall speed at full gross? Just curious, can't wait to launch mine.

AOA Critique

Posted: Mon Oct 29, 2007 4:53 pm

by Wes

Dave,
Very good comments on the AOA indicator. I've seen lots of these gadgets, but never flown behind one, so your critique is much appreciated.
I'm sold.
Thanks again,